The invention relates to a kitchen appliance having a container and a cover for the container and a tool drive means in the container and a drive arrangement disposed on the cover, for driving the tool drive means, means being provided with the aid of which the tool drive means can be braked after the drive arrangement has been switched off and the cover has been removed from the container.
Such a kitchen appliance of the type defined in the first paragraph has been put onto the market by the applicant under the type designation HR2831 and is consequently known. In connection with this known kitchen appliance reference can also be made to the patent document WO 98/58579 A1. During normal operation, while the substance to be processed is present in the container, the tool drive means of the known kitchen appliance is braked mainly and very rapidly by the processed substance present in the container. In the case of an unusual mode of operation of the known kitchen appliance, when the container is empty and the kitchen appliance is yet put into operation, i.e. while the drive arrangement is operative, after an electric motor forming part of the drive arrangement has been switched off the tool drive means is braked mainly by the electric motor and by the drive mechanism to be driven by this motor, which is caused by the bearing friction in the motor, by the brush friction in the motor and by the friction in the drive mechanism provided between the motor and the tool drive means. In the case of normal use of the known kitchen appliance in an unusual mode, i.e. when the container is empty, the turned-off electric motor also ensures a sufficiently effective and rapid braking of the tool drive means and, consequently, of the tool coupled to the tool drive means. However, in the case of an unusual mode of operation of the kitchen appliance when the kitchen appliance is not used in accordance with the instruction manual, when during operation the cover is impermissibly removed from the container after or already while the drive arrangement and, consequently, the electric motor is switched off, the tool drive means and, as a result, the tool coupled thereto will coast so long that there is a risk that the person using the kitchen appliance reaches into the container and is injured by the coasting tool, which is formed by, for example, a cutter.
It is an object of the invention to preclude the potential risk described herembefore and to realize an improved kitchen appliance which complies with the most stringent safety regulations, for example the safety regulations in accordance with IEC-60335-2-14, which safety regulations stipulate that cutters of compact kitchen appliances should coast to standstill within 1.5 seconds after opening or removal of the cover.
In order to achieve the afore-mentioned object characteristic features in accordance with the invention have been provided in a kitchen appliance in accordance with the invention, so that a kitchen appliance in accordance with the invention can be characterized in the manner defined hereinafter, namely:
A kitchen appliance having a container, which is disposed on a work surface during operation of the kitchen appliances and which serves to hold a substance to be processed and which has a bottom wall and a circumferential wall having a container rim. The appliance includes a tool unit which is supported on a bearing protruding from the bottom wall, a cover, which is placed on the container in the area of the container rim and which has an opening for the passage of a portion of the tool unit and which is removable from the container, and, a drive, unit which is mounted on the cover and coupled to the tool unit during operation of the kitchen appliance and thereby positions the tool unit in a driving position. The drive unit is removable from the cover and disengageable from the tool unit. The portion of the tool unit which passes through the lid opening has clearance sufficient to permit tilting of the tool unit when the drive unit is removed, and tool unit has a lower end which includes a bearing arrangement which engages the bearing which protrudes from the container bottom. The bearing arrangement also allows pivotal movement of the tool drive means about the protruding bearing means of the container. The lower end of the tool unit also includes a brake element which protrudes downward and is spaced radially outward and remote from the bearing arrangement, and has clearance from the container bottom wall when the tool unit is not tilted. The braking function is therefore disabled when the tool unit is coupled to the drive unit and is thus positioned in its driving position. The brake means produces a braking action by engaging the bottom wall of the container as a result of the pivotal movement of the tool unit when the tool unit is disengaged from the drive unit and thus allows the tool unit to perform a pivotal movement.
As a result of the provision of the measures in accordance with the invention it is achieved in a constructionally simple and very cheap yet highly reliable manner that the tool unit in the container is braked particularly effectively and therefore rapidly, as a result of which after switching off and after removal of the cover from the container the tool unit can now keep on running only for such a short time that it is substantially impossible for a user to come into contact with a tool which is coupled to the drive unit and is still in motion, because the time required for access to drive unit and the tool in the container is longer than the run-out time.
It has proved to be very advantageous when the brake is arranged to protrude axially from the lower end region of the tool unit because in this case the brake can exert braking action in the area of the bottom wall regardless of whether the cover is removed or is not removed from the container.
The brake may take the form of, for example, a brake block which enters into operational engagement with the bottom wall of the container as a result of a pivotal movement of the tool drive means. However, it has proved to be particularly advantageous when the brake is formed by a an annular brake ring because this guarantees a braking performance which is independent of a given locally bounded position.
It has also proved to be very advantageous when the brake ring consists of an elastomer, because such a brake ring provides a particularly good braking performance. However, it is alternatively possible to use other materials, for example synthetic materials having a high coefficient of friction.
The aforementioned aspects as well as further aspects of the invention will be apparent from the example of an embodiment described hereinafter and will be elucidated with the aid of this example.